Five years of funding are requested for the establishment of a Prevention Research Center, focused on the continued development of theoretical models that guide the development of integrated programs designed to prevent Conduct Disorders. Both the theory and prevention programs that will be evaluated are based on the central assumption that the early development of Conduct Disorder is embedded in the interaction between parent and child, most specifically in how the parents deal with child oppositional and aggressive behavior, and how they provide supervision and support when the child makes the critical transition to the school and peer group. Multi- measure longitudinal data bases available at our center make it possible to conduct tests of our models over most of the life span relevant to the development of Conduct Disorder. Twenty years of intervention research with aggressive youngsters that has been derived from those models provides the basis for the prevention strategies. Five integrated components are proposed to carry out project goals: first, a center core component is described that will facilitate the integrated development and assessment of the theoretical, assessment, and prevention models of Conduct Disorder; second, a component is described to carry a set of fifth grade prevention trials; third, a component is described to carry out first grade prevention trials; fourth, a component is described to conduct extensive theoretical and methodological analyses, and to use the trials data to conduct experimental tests of the theoretical models; fifth, a component is described to conduct pilot work on both intervention and assessment issues.